ConfigDrive: duplicated target for disk sources with Q35 machine type

[rajujith]

problem

With the Q35 machine type, which is the default on many recent libvirt versions or set intentionally per VM/template as per the requirements attaching 4th volume (3rd data volume) fails for running VM. It can be attached to a stopped VM.

Error:

Failed to attach volume vol4 to VM scsi-3; org.libvirt.LibvirtException: XML error: target 'sde' duplicated for disk sources '/mnt/f18be102-4fc9-36c8-a322-02b8e9674714/i-2-1936-VM.iso' and '/mnt/b75b9349-4d30-30dd-84ca-1de657c42cbf/30078d45-68d2-4e9b-ae53-16e49e73c795'

versions

4.22.1

The steps to reproduce the bug

1. Create an L2 guest network with the offering 'DefaultL2NetworkOfferingConfigDrive'
2. Register two templates with the following template settings
   rootDiskController:scsi, kvm.guest.os.machine.type:pc-q35-rhel9.6.0,UEFI=LEGACY
   rootDiskController:virtio, kvm.guest.os.machine.type:pc-q35-rhel9.6.0,UEFI=LEGACY
3. Deploy an instance in the L2 network using each template , attach 3 data volumes, 4th one fails to attach.

What to do about it?

Allow attaching the 4th volume.